The introduction of a reflective essay should begin with
a. a lead-in sentence.
b. a thoughtful question.
c. a thesis statement.
d. an acknowledgement of the audience.

b. a thoughtful question

Reflective essay is a type of essay that makes you introspect and cogitate about a certain phenomenon in one's experiences or a scenario a person has gone through.

If I were an animal, I would rather be a Lion. I would laze the whole day under the  shade of the acacia tree, away from the hot baking sun of the African savannah. In the cool of the evening, as the setting sun bids the day good night and the moon rises majestically into the beautiful starry sky, I would take a stroll to the cool water of the rushing river, parting the reeds and lush green ferns as I wend my way to the gently sloping bank and on to the clear sparkling water, and drink my fill to the tune of chirping crickets and mighty wing beats of the night fowl swishing through the lovely night on to their errands.With a contented, refreshed sigh, I would  rise and ever so quietly slip back into the green luxurious curtain of grass,...

The answer is a) carbon-12